This invention relates generally to digital communication networks and more particularly, it relates to a preamble search and synchronizer circuit used with digital receiver circuitry in a StarLAN coded data transceiver for reception of local area network messages.
In StarLAN (an acronym for Star Local Area Network) methodology which is governed by proposed specification IEEE P802.3-86/0.06G entitled "Physical Signaling, Medium Attachment, and Baseband Medium Specifications, Type 1 Base 5", a serial data input signal containing a preamble pattern must be transmitted at the beginning of a frame transmission prior to the start of a serial data packet (message). This preamble pattern in the data input signal is required to be detected and synchronized with a clock signal generated within the receiver circuitry of the transceiver for producing a synchronized signal which activates or enables a Manchester code detector circuit.
It would therefore be desirable to provide a preamble search and synchronizer circuit like that of the present invention which allows for the rapid detection of the preamble pattern in the data input signal and synchronizes it with the clock signal to produce a synchronized signal. By selection of circuit components and functions, the preamble search and synchronizer circuit of the instant invention is capable of being fabricated with a StarLAN coded transceiver as a part of a single monolithic integrated circuit in a compact and efficient configuration.